This invention relates to a master cylinder and method for manufacturing the same.
A master cylinder assembly includes a housing defining a bore (11) for movably receiving a pair of pistons (32, 34) a pair of sealing members (28, 30) cooperating with the pair of pistons (32, 34) to substantially define a pair of pressure chambers (42, 44), a sleeve (26) disposed within the housing bore to define substantially fixed positions for the pair of sealing members and a reservoir (40) coupled to the housing, the reservoir communicating with the housing bore to permit fluid carried within the reservoir to communicate with the housing bore, and the pair of pistons being movable during braking to generate fluid pressure within the pair of pressure chambers.
In U.S. Pat. No. 4,249,381, a sleeve is disposed within a master cylinder housing to define positions for fixedly locating a pair of sealing assemblies. In order to accurately locate the sleeve within the housing, it is necessary to machine a housing bore after the housing is formed by die casting or other suitable operations. Also, a reservoir is integrally defined by the housing and if the housing is made from a metal the reservoir will add more weight than if the reservoir is defined by a lightweight plastic material.
The machining operation increases the cost of the master cylinder assembly and also increases the time required to manufacture the master cylinder assembly. Also, the integrally formed metal reservoir increases the weight of the master cylinder housing.